Android课程---简单的音乐播放器

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.hanqi.test2.MusicPlay1"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="播放状态："
        android:id="@+id/tv_1"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="播放"
            android:onClick="play_onclick"/>

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="暂停"
            android:onClick="pause_onclick"/>

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="停止"
            android:onClick="stop_onclick"/>

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="退出"
            android:onClick="exit_onclick"/>

    </LinearLayout>

</LinearLayout>

package com.hanqi.test2;

import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;

public class MusicPlay1 extends AppCompatActivity {
    TextView tv_1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_music_play1);

        tv_1 =(TextView)findViewById(R.id.tv_1);

        tv_1.setText("播放状态:停止播放");

    }

    //媒体播放器的类
    private MediaPlayer mediaPlayer;

    public void play_onclick(View v)
    {
        if (mediaPlayer == null) {
            //调用MediaPlayer的静态方法create()
            mediaPlayer = MediaPlayer.create(this, R.raw.love);
        }
        mediaPlayer.start();

        tv_1.setText("播放状态:正在播放...");

    }
    public void stop_onclick(View v)
    {
        if (mediaPlayer != null) {
            mediaPlayer.stop();  //停止
            mediaPlayer.reset();  //重置
            mediaPlayer.release();  //释放资源
            mediaPlayer = null;  //赋空
        }
        tv_1.setText("播放状态:停止播放");

    }
    public void pause_onclick(View v)
    {
        //isPlaying:状态
        if (mediaPlayer != null && mediaPlayer.isPlaying())
        {
            mediaPlayer.pause();

            tv_1.setText("播放状态:暂停播放");
        }
    }
    public void exit_onclick(View v)
    {
        stop_onclick(v);

        finish();
    }
}

package com.hanqi.test2;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;

public class MusicPlay2 extends AppCompatActivity {
    TextView tv_1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_music_play1);

        tv_1 =(TextView)findViewById(R.id.tv_1);

        tv_1.setText("播放状态:停止播放");

    }


    public void play_onclick(View v)
    {
        Intent intent = new Intent(this,MusicPlayService.class);

        intent.putExtra("action","play");

        startService(intent);

        tv_1.setText("播放状态1:正在播放...");
    }
    public void stop_onclick(View v)
    {
        Intent intent = new Intent(this,MusicPlayService.class);

        intent.putExtra("action","stop");

        startService(intent);

        tv_1.setText("播放状态1:停止播放");
    }
    public void pause_onclick(View v)
    {
        Intent intent = new Intent(this,MusicPlayService.class);

        intent.putExtra("action","pause");

        startService(intent);

        tv_1.setText("播放状态1:暂停播放");
    }
    public void exit_onclick(View v)
    {
        stop_onclick(v);

        finish();
    }
}

package com.hanqi.test2;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;

public class MusicPlayService extends Service {
    public MusicPlayService() {
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }
    private MediaPlayer mediaPlayer;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        //获取意图传递的信息
        String action = intent.getStringExtra("action");
        switch (action)
        {
            case "play":

                if (mediaPlayer == null)
                {
                    mediaPlayer = MediaPlayer.create(this,R.raw.love);
                }

                mediaPlayer.start();

                break;

            case "stop":
                if (mediaPlayer != null)
                {
                    mediaPlayer.stop();
                    mediaPlayer.reset();
                    mediaPlayer.release();
                    mediaPlayer = null;
                }
                break;
            case "pause":
                
                mediaPlayer.pause();
                break;
        }
        return super.onStartCommand(intent, flags, startId);
    }
}